Patent Application
20150226041
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The present invention relates to controlling the flow of fluids and, more particularly, to the valve arrays used to control the flow of well fluids in a subterranean well tool. Still, more particularly, the present invention relates to the method and apparatus for using layers containing micro check valve arrays to control the flow of fluids in subterranean well filters.
Well filters are typically used in subterranean well environments in which it is desired to remove a liquid or gas from the ground, without bringing soil particulates, such as sand or clay, up with the liquid or gas. A well filter generally includes an inner support member, such as a perforated core and a filter body, including a filter medium disposed around the inner support member. In many cases, the well filter will further include an outer protective member, such as a perforated cage or shroud, disposed around the filter body for protecting it from abrasion and impacts. A filter for subterranean use is described in U.S. Pat. No. 6,382,318, which is hereby incorporated herein by reference for all purposes. A downhole screen and method of manufacture is described in U.S. Pat. No. 5,305,468, which is hereby incorporated herein by reference for all purposes. A downhole sand screen with a degradable layer is described in U.S. Pub. No. 2005/0155772, which is hereby incorporated herein by reference for all purposes.
It is desirable to be able to provide a flow path through the screen to provide circulation, while installing the screen in a well. In the past, such circulation has been provided by a washpipe extending through the screen. The washpipe permits fluid to be circulated through the screen before, during and after the screen is conveyed into the well, without allowing debris, mud, etc. to clog the screen. However, using a washpipe requires additional operations when completing the well for production of hydrocarbons.
Expandable and nonexpandable screens have been used in the past, either with or without the use of a washpipe. When a washpipe is not used, there is no sealed fluid path through the screen to allow fluids to be pumped from the top of the screen to the bottom. As a result, any attempt to circulate fluid in the well would result in large volumes of fluid being pumped through the screen media, potentially plugging or clogging the screen and potentially damaging the surrounding hydrocarbon bearing formation.
Degradable materials have been used and proposed in the past to completed block flow through the screen. These prior systems involve materials that dissolve or degrade over time when placed in the well. However, while the blocking materials degrade these systems prevent production from the well during degradation.
Accordingly, there is a need for improved methods and apparatus to permit circulation through an expandable well screen during its installation in a well, while not requiring additional well operations associated with use of a washpipe and which allow production to begin immediately, once treating fluid circulation ceases. Other benefits could also be provided by improved methods and systems for installing well screens in a well.
Disclosed herein are subterranean well tools and a method for use in a well at a subterranean location. In an embodiment, sand screen is provided without the need of a washpipe. The screen is assembled with a circumferential layer, comprising an array of micro valves, which restricts or substantially blocks flow radially outward from the screens interior, yet open to permit flow through the screen from the exterior into the interior. The micro valves in the array act as check valves, preventing treating fluids pumped down the well to escape from the well through the screen and immediately allow flow from the formation to enter the well through the screen. In addition, the layer of micro valves can be constructed from materials that degrade or dissolve over time in the presence of well fluids. The method includes the steps of: providing the screen, including a permanent or degradable micro valve layer which prevents fluid flow out of the well through a wall of the screen; and positioning the screen in a wellbore, pumping well fluids through the screen, while preventing these fluids from escaping from the well through the screen and immediately thereafter permitting fluid flow into the well through the screen. It is envisioned that well tools, utilizing selective flow control through layered material, could be provided.
For a more complete understanding of the present disclosure and the advantages thereof, reference is now made to the following brief description, taken in connection with the accompanying drawings and detailed description:
In the drawings and description that follow, like parts are typically marked throughout the specification and drawings with the same reference numerals, respectively. The drawing figures are not necessarily to scale. Certain features of the invention may be shown exaggerated in scale or in somewhat schematic form, and some details of conventional elements may not be shown in the interest of clarity and conciseness.
Unless otherwise specified, any use of any form of the terms “connect,” “engage,” “couple,” “attach,” or any other term describing an interaction between elements is not meant to limit the interaction to direct interaction between the elements and may also include indirect interaction between the elements described. In the following discussion and in the claims, the terms “including” and “comprising” are used in an open-ended fashion, and thus should be interpreted to mean “including, but not limited to.” Reference to “up” or “down” will be made for purposes of description with “up,” “upper,” “upward,” or “upstream” meaning toward the surface of the wellbore and with “down,” “lower,” “downward,” or “downstream” meaning toward the terminal end of the well, regardless of the wellbore orientation. The term “zone” or “pay zone” as used herein refers to separate parts of the wellbore designated for treatment or production and may refer to an entire hydrocarbon formation or separate portions of a single formation, such as horizontally and/or vertically spaced portions of the same formation.
The various characteristics mentioned above, as well as other features and characteristics described in more detail below, will be readily apparent to those skilled in the art with the aid of this disclosure upon reading the following detailed description of the embodiments and by referring to the accompanying drawings.
Referring now to the drawings, wherein like reference characters are used throughout the several views to indicate like or corresponding parts, there is illustrated in
As will be described in more detail, the outer layers of the sand screen assembly 10 have their ends crimped onto the base pipe 20, as indicated by reference numeral 16. The base pipe 20 includes perforations 22, extending through the wall of the base pipe 20 along the length between the crimped and 16. As used herein, the term “perforation” is not intended to be cross section-shaped limiting and includes all shapes, for example, perforations which are circular, oblong, and slit shaped. As is well known in the industry, these openings in the base pipe need only be of a sufficient size and shape to facilitate flow without destroying the structural integrity of the base pipe.
As best illustrated in
Preferably, at least one valve layer 100 is included in the screen assembly. In the
As best illustrated in
As illustrated in
Material used to form the valves depends on the application, for example, in general scenarios where corrosive resistant is a requirement, 200 and 300 grade stainless materials like 202, 301, 304, 304L(H), 316 (L) may be used. However, other materials like non-ferrous materials and polymer materials may also be considered in case of low strength requirements or small scales. The sheet can be fabricated from a metal or metal alloy, such as steel, stainless steel, titanium alloys, aluminum alloys, nickel alloys. The sheet can be fabricated from a plastic, such as a thermoplastic, a thermoset plastic, PEEK, Teflon, and these plastics can be reinforced with fibers, such as a carbon fiber composite or with particles, such as a filled Teflon. The sheet can be formed from an elastomer, a hinged ceramic or glass, a fabric, a mesh, a composite or any other material or combination of materials suited to the task. In well tool embodiments (for example, the sand screen), the array 102 is installed with inner layer 104 on the side from which flow is restricted and outer layer 108 on the side from which flow is allowed. In
As illustrated in
Outer sheet 108 has an array of openings 118 positioned to have the same spacing as to tab-shaped valve elements, so that, when sheets 104 and 106 are joined together the openings 118 and valves elements are aligned. Openings 118 are selected to be slightly smaller than the valves elements to form an annular seat 120 for the valve element to seal against. Inner sheet 104 contains openings 124. Openings 124 are larger than valves 110 and are spaced to align with the valves elements. Openings 124 provide clearance for the valve element to pivot to the open position, as illustrated in
Slot 220 is connected at its right-hand end to a thinner slot 230 and at its left-hand end to a thin slot 240. A bypass slot 260 connects slot 230 to the intermediate portion of slot 220.
In operation as fluid moves into slot 240, it will cause a valve element 210 to move to the position illustrated in
If conditions surrounding the valve are such that fluid attempts to flow into the valve 200 through slot 230 in the direction of arrow R, the valve element 210 will move to the left-hand side as illustrated in
In
In the case of high pressure drop across the valve, and in the corrosive resistant environments, the 202, 301, 304, 304L(H), or 316(L) stainless materials may be used. The diameters of the valve could range from mm meter to cm meter scale. Accordingly, the thickness should be generally of a lower scale after a calculation based on the material strength and the bending angle requirements. Nonmetal material will have smaller diameter and relatively be thinner with the application of the low pressure drop across the valve. Each layer can range from 0.002 inches to 0.25 inches. Spacing can range from one per tubing joint to one per square centimeter. The valve diameter can range from ½ the layer thickness to over 50 times the layer thickness.
According to another feature of the present invention, the valve layer 100 can be made of material that degrades or dissolves over time or in the presence of certain materials. This has the advantage of allowing screen installation and well completion processes to be performed with the valve layer 100 in place and has the further advantage of further enhancing production by removing the valve layer.
As used herein, a degradable material is capable of undergoing an irreversible degradation downhole. The term “irreversible” as used herein means that the degradable material once degraded should not recrystallize or reconsolidate while downhole in the treatment zone, that is, the degradable material should degrade in situ but should not recrystallize or reconsolidate in situ.
The terms “degradable” or “degradation” refer to both the two relatively extreme cases of degradation that the degradable material may undergo, that is, heterogeneous (or bulk erosion) and homogeneous (or surface erosion), and any stage of degradation in between these two. Preferably, the degradable material degrades slowly over time, as opposed to instantaneously.
The degradable material is preferably “self-degrading.” As referred to herein, the term “self-degrading” means bridging may be removed without the need to circulate a separate “clean up” solution or “breaker” into the treatment zone, wherein such clean up solution or breaker have no purpose other than to degrade the bridging in the proppant pack. Though “self-degrading,” an operator may nevertheless elect to circulate a separate clean up solution through the well bore and into the treatment zone under certain circumstances, such as when the operator desires to hasten the rate of degradation. In certain embodiments, a degradable material is sufficiently acid-degradable is to be removed by such treatment. In another embodiment, the degradable material is sufficiently heat-degradable to be removed by the wellbore environment.
The degradation can be a result of, inter alia, a chemical or thermal reaction or a reaction induced by radiation. The degradable material is preferably selected to degrade by at least one mechanism selected from the group consisting of: hydrolysis, hydration followed by dissolution, dissolution, decomposition or sublimation.
The choice of degradable material can depend, at least in part, on the conditions of the well, e.g., wellbore temperature. For instance, lactides can be suitable for lower temperature wells, including those within the range of about 60° F. to about 150° F., and polylactides can be suitable for well bore temperatures above this range. Dehydrated salts may also be suitable for higher temperature wells.
In choosing the appropriate degradable material, the degradation products that will result should also be considered. It is to be understood that a degradable material can include mixtures of two or more different degradable compounds.
As for degradable polymers, a polymer is considered to be “degradable” herein if the degradation is due to, inter alia, chemical or radical process such as hydrolysis, oxidation, enzymatic degradation or UV radiation. The degradability of a polymer depends, at least in part, on its backbone structure. For instance, the presence of hydrolyzable or oxidizable linkages in the backbone often yields a material that will degrade as described herein. The rates at which such polymers degrade are dependent on the type of repetitive unit, composition, sequence, length, molecular geometry, molecular weight, morphology (e.g., crystallinity, size of spherulites, and orientation), hydrophilicity, hydrophobicity, surface area, and additives. Also, the environment to which the polymer is subjected may affect how the polymer degrades, e.g., temperature, presence of moisture, oxygen, microorganisms, enzymes, pH, and the like.
Some examples of degradable polymers are disclosed in U.S. Patent Publication No. 2010/0267591, having named inventors Bradley L. Todd and Trinidad Munoz, which is incorporated herein by reference. Additional examples of degradable polymers include, but are not limited to, those described in the publication, Advances in Polymer Science, Vol. 157, entitled “Degradable Aliphatic Polyesters.” edited by A. C. Albertsson and the publication, “Biopolymers,” Vols. 1-10, especially Vol. 3b, Polyester II: Properties and Chemical Synthesis and Vol. 4, Polyester III: Application and Commercial Products, edited by Alexander Steinbuchel, Wiley-VCM.
Some suitable polymers include poly(hydroxy alkanoate) (PHA); poly(alpha-hydroxy) acids, such as polylactic acid (PLA), polygylcolic acid (PGA), polylactide, and polyglycolide; poly(beta-hydroxy alkanoates), such as poly(beta-hydroxy butyrate) (PHB) and poly(beta-hydroxybutyrates-co-beta-hydroxyvelerate) (PHBV); poly(omega-hydroxy alkanoates) such as poly(beta-propiolactone) (PPL) and poly(ε-caprolactone) (PCL); poly(alkylene dicarboxylates), such as poly(ethylene succinate) (PES), poly(butylene succinate) (PBS); and poly(butylene succinate-co-butylene adipate); polyanhydrides, such as poly(adipic anhydride); poly(orthoesters); polycarbonates, such as poly(trimethylene carbonate); and poly(dioxepan-2-one)]; aliphatic polyesters; poly(lactides); poly(glycolides); poly(ε-caprolactones); poly(hydroxybutyrates); poly(anhydrides); aliphatic polycarbonates; poly(orthoesters); poly(amino acids); poly(ethylene oxides); and polyphosphazenes. Of these suitable polymers, aliphatic polyesters and polyanhydrides are preferred. Derivatives of the above materials may also be suitable, in particular, derivatives that have added functional groups that may help control degradation rates.
Of the suitable aliphatic polyesters, poly(lactide) is preferred. Poly(lactide) is synthesized, either from lactic acid by a condensation reaction or, more commonly, by ring-opening polymerization of cyclic lactide monomer. Since both lactic acid and lactide can achieve the same repeating unit, the general term “poly(lactic acid)” as used herein refers to Formula I, without any limitation as to how the polymer was made, such as from lactides, lactic acid or oligomers, and without reference to the degree of polymerization or level of plasticization.
The lactide monomer exists generally in three different forms: two stereoisomers (L- and D-lactide) and racemic DL-lactide (meso-lactide).
The chirality of the lactide units provides a means to adjust, inter alia, degradation rates, as well as physical and mechanical properties. Poly(L-lactide), for instance, is a semicrystalline polymer with a relatively slow hydrolysis rate. This could be desirable in applications where a slower degradation of the degradable material is desired. Poly(D,L-lactide) may be a more amorphous polymer with a resultant faster hydrolysis rate. This may be suitable for other applications where a more rapid degradation may be appropriate. The stereoisomers of lactic acid may be used individually or combined. Additionally, they may be copolymerized with, for example, glycolide or other monomers like ε-caprolactone, 1,5-dioxepan-2-one, trimethylene carbonate, or other suitable monomers to obtain polymers with different properties or degradation times. Additionally, the lactic acid stereoisomers can be modified to be used by, among other things, blending, copolymerizing or otherwise mixing the stereoisomers, blending, copolymerizing or otherwise mixing high and low molecular weight polylactides, or by blending, copolymerizing or otherwise mixing a polylactide with another polyester or polyesters. See U.S. Application Publication Nos. 2005/0205265 and 2006/0065397, incorporated herein by reference. One skilled in the art would recognize the utility of oligmers of other organic acids that are polyesters.
Certain anionic compounds that can bind a multivalent metal are degradable. More preferably, the anionic compound is capable of binding with any one of the following: calcium, magnesium, iron, lead, barium, strontium, titanium, zinc or zirconium. One skilled in the art would recognize that proper conditions (such as pH) may be required for this to take place.
A dehydrated compound may be used as a degradable material. As used herein, a dehydrated compound means a compound that is anhydrous or of a lower hydration state, but chemically reacts with water to form one or more hydrated states, where the hydrated state is more soluble than the dehydrated or lower hydrated state.
After the step of introducing a well tool, comprising a degradable material, the methods can include a step of allowing or causing the degradable material to degrade. This preferably occurs with time under the conditions in the zone of the subterranean fluid. It is contemplated, however, that a clean-up treatment could be introduced into the well to help degrade the degradable material.
According to the method of the present invention a well tool can be assembled comprising a fluid directional controlling valve layer. The tool such as a sand screen can be assembled in the string and placed in the well in a subterranean location. Subsequently well completion and treatment fluids can be produced into the well through the tubing all the valve layer controls flow of fluids from the tubing through the tool. After the well is treated, production can commence. In some embodiments, an additional step of degrading the materials, forming the valve layer can occur.
While compositions and methods are described in terms of “comprising,” “containing,” or “including” various components or steps, the compositions and methods also can “consist essentially of” or “consist of” the various components and steps. As used herein, the words “comprise,” “have,” “include,” and all grammatical variations thereof are each intended to have an open, non-limiting meaning that does not exclude additional elements or steps.
Therefore, the present inventions are well adapted to carry out the objects and attain the ends and advantages mentioned as well as those which are inherent therein. While the invention has been depicted, described, and is defined by reference to exemplary embodiments of the inventions, such a reference does not imply a limitation on the inventions, and no such limitation is to be inferred. The inventions are capable of considerable modification, alteration, and equivalents in form and function, as will occur to those ordinarily skilled in the pertinent arts and having the benefit of this disclosure. The depicted and described embodiments of the inventions are exemplary only, and are not exhaustive of the scope of the inventions. Consequently, the inventions are intended to be limited only by the spirit and scope of the appended claims, giving full cognizance to equivalents in all respects.
Also, the terms in the Claims have their plain, ordinary meaning unless otherwise explicitly and clearly defined by the patentee. Moreover, the indefinite articles “a” or “an,” as used in the claims, are defined herein to mean one or more than one of the element that it introduces. If there is any conflict in the usages of a word or term in this specification and one or more patent(s) or other documents that may be incorporated herein by reference, the definitions that are consistent with this specification should be adopted.
| Filing Document | Filing Date | Country | Kind |
|---|---|---|---|
| PCT/US2012/062416 | 10/29/2012 | WO | 00 |
